The present invention is directed to control devices for bicycle transmissions and, more particularly, to a force transfer mechanism for a bicycle transmission control cable.
Bicycle transmissions are commonly controlled by a manually operated shift control unit that includes a lever or ring that is rotated by the rider. The shift control unit is connected to a control cable of the type having an inner wire that slides within a tubular outer casing, wherein one end of the inner wire is connected to the shift control unit, and the other end of the inner wire is connected to the bicycle transmission. The transmission may be a derailleur or internal hub transmission, wherein operation of the shift control unit selectively pulls or releases the inner wire to change gears in the transmission. Such transmissions are usually located at the pedal cranks (a front transmission) and/or the rear wheel (a rear transmission). Bicycles operated with derailleurs, by the far the most common types of bicycle transmission, usually have both front-and rear transmissions. With such bicycles the shift control unit for the front transmission is usually mounted at the left gripping end of the handlebar, and the shift control unit for the rear transmission is usually mounted at the right gripping end of the handlebar.
Typical shift control units usually include a pulley which winds or unwinds the inner wire in response to rotation of the manually operated lever or ring. The cable winding groove on the pulley may have various configurations such as circular, increasing radius, decreasing radius, etc. to produce a rate of pulling or releasing of the inner wire to accommodate the gear shifting motion characteristics of the transmission. As a result, different shift control units usually must be made to accommodate different transmissions.
Additionally, some shift control units have a gear indicator for indicating the current gear position of the bicycle transmission. Some gear indicators take the form of a disc or needle that rotates in repose to rotation of the pulley. Other gear indicators are simple markings on the manually operated lever or ring that move relative to a stationary scale on the shift control unit housing. In any case, the gear indicator is located with the shift control unit housing. Consequently, since the shift control units are usually mounted at the opposite gripping ends of the handlebar, the rider must divert his or her view from the road or trail and look to the opposite ends of the handlebar to ascertain the currently selected gears. This is very inconvenient, especially during races since full awareness of the race course and nearby riders is required to win the race.
The present invention is directed to a force transfer unit for a bicycle transmission which can be used with multiple types of shift control devices and/or which allows the rider to ascertain the gear position or state of one or more bicycle transmissions while looking straight ahead. In one embodiment of the present invention, a force transfer unit is provided for engaging a control cable connected to a hand operated shift control unit. The force transfer unit includes a handlebar attachment member and a cable diverting member for changing a direction of the control cable, wherein the force transfer unit is separate from the shift control unit. In a more specific embodiment, the cable diverting member takes the form of a pulley, wherein a cable winding groove of the pulley has the appropriate shape to accommodate the cable pulling requirements of the shift control device. Thus, the force transmission mechanism can be used with different types of shift control units, and shift control units having different cable pulling requirements can be accommodated merely by changing the pulley in the force transfer unit. The force transfer unit can be placed in a convenient place such as the central portion of the handlebar. With this configuration the control cable may extend conveniently from the shift control unit parallel to the handlebar and then be diverted to extend parallel to the bicycle frame.
In another embodiment, the force transfer unit may include a gear indicator for indicating a current gear of the bicycle transmission. If the force transmission unit is mounted in the central portion of the handlebar, then the rider can ascertain the current gear of the bicycle transmission without having to look to the ends of the handlebar. This is especially convenient when the force transfer unit is used with combined front and rear bicycle transmissions.